The present disclosure relates to a xerographic printing system. More specifically, this disclosure relates to a sheet feeder system and method for feeding sheets to one or more printing modules, the sheets being fed including any kind of media appropriate for use as a substrate for printing within a xerographic printing system.
As illustrated in FIG. 1, a conventional printing system includes one or more printing modules 2, 4, 6, 8, a feeder module 10 and a finisher module 12. The printing modules 2, 4, 6, and 8 may employ a variety of configurations that include horizontal alignment, vertical alignment or an integrated vertical/horizontal alignment configuration as illustrated in FIG. 1. In addition, a printing system can include a single printing module. In general, the sheet feeder module 10 feeds a sheet of paper, plastic or other suitable physical print media for images and text to the printing modules 2, 4, 6, and 8 by way of a sheet path which connects the feeder module 10 to the printing modules 2, 4, 6, and 8. The printing modules 2, 4, 6, and 8 include marking apparatuses that are used for applying an image to the sheet which is supplied from the feeder module. After marking has been completed within the printing modules, the sheet travels to a finishing module 12 which includes any post-marking devices, such as a sorter, mailbox, inserter, interposer, folder, stapler, stacker, hole puncher, collator, stitcher, binder, envelope stuffer, postage machine, or the like.
A conventional sheet feeder module can include one or more feeders, as illustrated in FIG. 1. A conventional friction retard feeder design is illustrated in FIG. 2. This conventional design includes a separation nip 20 having a forward driven feed roll 22 and a retard roll 24 that serves as a high drag torque idler. A nudger roll 26 is generally placed a short distance back from the lead edge of the sheet stack 28. The nudger roll 26 serves to advance the top sheet(s) off of the stack 28 and into the separation nip 20. This feeder configuration is well known within the industry. This feeder technology is hampered from operating a high speeds (>100 ppm) in part because of the variable amount of time it can take to nudge the top sheet into the feed nip, i.e. acquire the sheet. Sheet feeder timing is limited by the longest acquisition time possible while still delivering sheets within the pitch time tolerances to the system. Nudging of the top sheet cannot start until the previous sheet's trail edge has cleared the nudger 26 or more generally the separation nip 20 since the feed roll 22 and the nudger roll 26 drive is generally tied together mechanically.
This disclosure provides a system and method of increasing the sheet feed rate by the addition of a rear nudger.